Abstract:
We have conducted experiments on a periodically inhibited
oscillatory Belousov-Zhabotinksy (BZ) reaction-diffusion
system in a
regime in
which the patterns oscillate at half the frequency of the
forcing (the
2:1 resonance regime). The periodic perturbations of the
photosensitive (ruthenium-catalyzed) reaction are made with
light,
which inhibits the oscillatory behavior. Increasing the light
intensity increases the refractory period (time for recovery
from
inhibition), which decreases the oscillation frequency of
the patterns
in the medium. We investigate the behavior for two different
levels of
inhibitor concentration in the reagent feed to determine the
shape of
the 2:1 resonant regime as a function of the forcing
intensity and
forcing frequency. At high forcing intensity the inhibition
leads to
a transition from traveling waves (spirals) to standing waves.
Simulations of a reaction-diffusion model with FitzHugh-Nagumo
kinetics yield behavior similar to that observed in the
experiments.
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